Melanoma incidence rates continue to increase worldwide, despite widespread efforts at primary prevention based on sun exposure avoidance education. Childhood sun exposure not only increases melanoma risk, but also establishes lifetime patterns of sun exposure and protection. In many areas where specific primary prevention efforts involving childhood education have been adopted, little impact on the overall melanoma burden has been realized. This is most likely because, as a wealth of previous study has shown, there is a disconnect between knowledge of 'safe' sun exposures and any resulting behavioral change. Our objective in this study is to test a novel classroom-based hands-on educational intervention to motivate youth to limit their sun exposure, and affect sun exposure behavior change. We have been conducting a SunSmart educational program in Los Angeles area schools for 5 years, and aim to use those established relationships to ensure the success of this study. We will recruit at least 1,575 students from at least 18 schools to participate in a randomized trial of the effect our Intervention, the UV Dosimetry Laboratory (in comparison to SunSmart alone) in changing sun exposure behavior. We will establish baseline sun exposure knowledge, attitudes and behavior, conduct the Intervention, then conduct follow-up to determine if UV exposure behavior changed in a subset of at least 315 students. We will obtain baseline and follow-up UV exposure data using dosimeters measuring real change in sun exposure behavior. Our proposed approach is innovative, incorporating students' scientific discovery and personal understanding of their own UV exposures in an active educational intervention, and verifying behavior change using dosimetry. Our pilot data suggests a high probability of success of both the approach and the intervention itself. The potential impact of this study is far-reaching, because it is being conducted amongst the largest population of school children (a potential target population of almost 700,000 school children) exposed to the highest levels of UV in the country.